GB391012A - Improvements in or relating to safety devices for apparatus for opening doors - Google Patents

Abstract

391,012. Door-operating appliances. BERTELE, R., 3, Stradone Duomo, Verona, Italy. Aug. 25, 1932, No. 23801. [Class 65 (i).] In a door-operating appliance having a detent operated electrically, the circuit which operates the detent is only closed when a signalling circuit, adapted to be closed from the outside when the door is required to be opened, has been closed. In the arrangement shown, P is a part of the door-operating mechanism which is normally held against movement by a spring-controlled pivoted detent L held in engagement with the member P by the armature of an electromagnet E. The circuit of the electromagnet E, controlled by a pushbutton t, includes contacts a, normally open, operated by a spring-controlled crank R which is held in the position shown by the armature of a second electromagnet e. Pressing the pushbutton t therefore has no effect unless a button s has been pressed to energize the electromagnet e, the circuit of which also includes a signal bell V ; energization of e releases R to close contacts a, and if the button t is now pressed the electromagnet E is energized and the detent L is rendered free to be pushed aside by the member P of the dooroperating mechanism. When the member P moves, the detent L is forced against the crank R so that the latter again engages the armature of electromagnet e and allows the contacts a to open. The detent L is restored to its locking position, in engagement with the armature of electromagnet E, by its spring. In a modification, the contacts a are dispensed with and the crank R is arranged to hold the armature of electromagnet E in the normal position.